The present invention generally relates to liquid fuel cell systems, and, more particularly, to a liquid fuel cell system that has a structure in which a liquid fuel cartridge is connected to a liquid fuel cell unit so as to pour and supply liquid fuel that is a methanol solution into the liquid fuel cell unit. This easy-to-use liquid fuel cell system can be used as a power source for charging the battery of a portable electronic device or a power source of a portable electronic device.
A liquid fuel cell system that can be used as a power source for charging the battery of a portable electronic device or a power source of a portable electronic device may have a structure in which a suitable amount of liquid fuel for power consumption is supplied through a pump, or a simple structure in which a liquid fuel cartridge is attached to a liquid fuel cell unit so as to pour and supply liquid fuel into the liquid fuel cell unit. A liquid fuel cell system of the former structure is too large to be used as a power source of a portable electronic device. A liquid fuel cell system of the latter structure is small enough to be used as a power source of a portable electronic device.
In the conventional simple-type liquid fuel cell system, a liquid fuel cartridge is simply connected to a liquid fuel cell unit so as to pour and supply liquid fuel into the liquid fuel cell unit.
The above conventional simple-type liquid fuel cell system is used to supply a predetermined amount of liquid fuel from the liquid fuel cartridge to the liquid fuel cell unit, with the battery charging time and the usage time of the portable electronic device being taken into consideration. In a case where the battery charging and the use of the portable electronic device end earlier than expected, however, some liquid fuel remains in the liquid fuel cell unit even though electric power is not being consumed any more.
If this situation continues for a long time, the solid polymer films that form the cells might deteriorate due to the continuous contact with the liquid fuel. As the solid polymer films deteriorate, the service life of the liquid fuel cell is shortened.